Filter screen apparatus for the air outlet of a particle production apparatus

ABSTRACT

The invention relates to a filter screen for the air outlet of an apparatus used to produce solid sulphur particles from a stream of molten sulphur supplied to the apparatus. According to the invention the filter screen comprises a plurality of closely spaced resiliently deformable filter elements arranged across the air outlet. The advantage of this arrangement is that sulphur particles collected on the resiliently deformable filter elements can be easily removed by causing the filter elements to vibrate. The filter elements may take the form of coil springs arranged adjacent one another about the air outlet.

This is a division of application Ser. No. 799,681, filed Nov. 19, 1985,and issuing as U.S. Pat. No. 4,705,467 on Nov. 10, 1987.

BACKGROUND OF THE INVENTION

The invention relates to apparatus for producing solid sulphur particlesof molten sulphur supplied to the apparatus.

Apparatus of this kind is well-known and generally used for theproduction of solid sulphur particles or beads.

DESCRIPTION OF THE PRIOR ART

An example of such known apparatus comprises a hollow column, sulphurspray means in the upper part of the column, sulphur supply meansconnected to the sulphur spray means, an air inlet in the lower part ofthe column, air supply means connected to the air inlet, a collectingdevice in the lower part of the column for collecting the solid sulphurparticles produced, discharge means for removing the solid sulphurparticles produced from the column and an air outlet in the upper partof the column.

In this known apparatus molten sulphur is injected into the columnthrough the sulphur spray means and air is passed from the air inlet tothe air outlet of the column. The sulphur injected into the column iscooled by the air passing through the column and condenses in such amanner that solid sulphur particles or beads are formed. The solidsulphur particles or beads fall to the collecting device wherein theyare collected. From the collecting device the solid sulphur particles orbeads, which are the desired product, are discharged from the column.

In the column, a small part of the liquid and/or solid sulphur isentrained in the stream of air passing from the air inlet to the airoutlet. In order to minimize emission problems it is desirable toprovide the air outlet with a suitable filter. However, conventionalfilters have the disadvantage that any sulphur collected on the filterelements is difficult to remove and furthermore often represent asignificant obstruction to free air flow out of the air outlet, which isrequired for proper operation.

SUMMARY OF THE INVENTION

In order to solve or alleviate this problem in a simple and inexpensivemanner the invention provides a filter screen for the air outlet of anapparatus for producing solid sulphur particles, which filter screencomprises a plurality of closely spaced resiliently deformable filterelements arranged across the air oulet.

The resilient filter elements must be spaced in such a manner that theypresent a significant open area to the air flow out of the air outlet.The degree of obstruction to air flow caused by the resilient filterelements can be readily determined by persons skilled in the art.Surprisingly, it is found that such an array of the resilient filterelements is nevertheless effective at removing significant quantities ofsulphur fines. Clearly, however, if the array of resilient filterelements is too open, the effectiveness of the filter screen will bereduced. The resilient filter elements may for example be elongateelements mounted adjacent one another in close spacing and having endssupported on the periphery of the air outlet. Such resilient filterelements may have a partially open cross-section in the plane of the airoutlet. It has furthermore been found that the sulphur, normallydifficult to remove from surfaces in the apparatus, can be displaced bydeforming the resilient filter elements so that the surface bond isbroken.

In a suitable embodiment of the invention the resiliently deformablefilter elements are coil springs.

Preferably the coil springs are in at least partly extended condition;for example, the springs are extended to from 2.5 to 3 times theirunextended condition.

Not only do the springs effectively collect a significant part of thesulphur fines, but also the sulphur collected on the springs can besimply removed from the springs by causing the springs to vibrate.

These and other features, objects, and advantages of the presentinvention will become apparent from the following detailed description,wherein reference is made to the Figures in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. I shows a vertical cross-section of the apparatus;

FIG. II shows a horizontal cross-section H--H of the upper part of theapparatus according to FIG. I, but on a scale which is larger than thescale of FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The apparatus as shown in the drawings comprises a column 1 in the shapeof a hollow cylinder. In the upper part of the column 1 sulphur spraymeans 2 are present, for example a plurality of jacketed sulphur spraypods 2, which may be heated by means of steam during normal operation.

A sulphur reservoir 4 is provided with a sulphur supply conduit 3 forthe supply of molten sulphur to the reservoir 4. In the reservoir 4 asulphur pump 5 is present, which is connected to a drive motor 6, forexample, an electric motor, by means of a drive shaft 7.

The pressure side of the pump 5 is connected to the sulphur spray means2 by means of a sulphur supply conduit 8. The supply conduit 8 ispreferably provided with a jacket, so that the contents of the conduit 8may be heated by means of steam during normal operation. A sulphurfilter 9 may be arranged in the conduit 8, if desired.

A plurality of air inlets 13 is arranged in the lower part of thecolumn 1. These air inlets 13 are connected to an air blower 11 by meansof an air supply conduit 12.

Furthermore, the lower part of the column 1 is provided with acollecting device 19 for collecting the solid sulphur particles or beads21 produced in the column 1. Below the collecting device 19, a suitableconveyor 20 is present for transporting the sulphur particles 21 fromthe collecting device 19 to a suitable destination.

The top of the column 1 is provided with an end wall 17 and the upperpart of the column 1 is provided with one or more air outlets. In theembodiment shown there is an outer air outlet 14 and an inner air outlet18.

Across the outer air outlet 14, a plurality of coil springs 15 arearranged adjacent to one another and along an imaginary cylinder 22,(shown in FIG. II) in such a manner that said springs 15 form a closelyspaced filter screen across the air outlet 14. In the same way, acrossthe inner air outlet 18, a plurality of coil springs 16 are arrangedadjacent to one another and along an imaginary cylinder 23, in such amanner that said springs 16 form a closely spaced filter screen acrossthe air outlet 18. The springs 15 and 16 are preferably in extendedcondition; they are for example extended to from 2.5 to 3 times theirunextended length.

During normal operation of the apparatus described in the above, moltensulphur is pumped by pump 5 from the reservoir 4 and through the conduit8 to the sulphur spray means 2. The liquid sulphur is injected into theupper part of the column 1 by the spary means 2. At the same time theair blower 11 supplies air through conduit 12 to the air inlets 13, sothat air is injected into the lower part of the colunm 1 by means of theair inlets 13. The air injected into the column 1 passes from the airinlets 13 upwards through the column 1 and leaves the column 1 via theair outlets 14 and 18, as shown respectively by the arrows B and A.

The molten sulphur injected into the column 1 through the spray means 2is cooled by the air passing through the column 1 and condenses in sucha manner that solid sulphur particles or beads 21 are formed. The solidsulphur particles or beads 21 fall to the collecting device 19, whereinthey are collected. The solid sulphur particles or beads 21 are passedfrom the collecting device 19 to the conveyor 20 which transports thesolid sulphur particles 21, which are the desired product, to a suitabledestination.

In the column 1, a small part of the liquid and/or solid sulphur isentrained in the stream of air passing from the air inlets 13 to the airoutlets 14 and 18. In order to minimize emission problems, it isdesirable to provide the air outlets 14 and 18 with filter elements.

Suitable filter elements according to the invention are the coil springs15 and 16 which are arranged across the air outlets 14 and 18respectively. Sulphur 1 carried in the air passing through the outlets14 and 18 adheres to the springs 15 respectively 16 by electrostaticattraction, or settling and sticking.

The sulphur 21 collected on the springs 15 and 16 is removed byperiodically causing said springs 15 and 16 to vibrate therebydislodging the sulphur 21 collected on the springs 15 and 16. Forexample, it is possible to hit one spring 15 causing it to vibrate,whereafter said spring 15 transmits the vibration to adjacent springs15, so that the sulphur 21 will be removed from these adjacent springs15 as well. Consequently, by hitting only a few springs 15, it ispossible to cause all the springs 15, 16 to vibrate, so that the sulphur21 will be removed from all the springs 15 and 16. The sulphur particles21 dislodged from the springs 15 and 16 may fall back into the colunm 1and be collected together with the sulphur beads 21 in the collectingdevice 19.

Different kinds of coil springs 15 and 16 may be used for the abovepurpose.

For example, 15 mm mean diameter coil springs 15 and 16 may be made of1.5 mm diameter steel wire, helically wound and extended to from 2.5 to3 times their unextended length. The springs 15 and 16 may be soarranged that they are spaced apart from each other, for example, with aclearance of about 1 mm. Alternatively, they may be so arranged in theextended condition that they are in permanent contact with each other.The springs may be provided with a suitable coating, for example, atetrafluoroethylene coating.

In the embodiment of the apparatus as described two air outlets arepresent. Instead it is possible to provide the apparatus with a singleair outlet or more than two air outlets.

In the embodiment of the apparatus as described the resilientlydeformable filter elements are coil springs. It is however, alsopossible to use instead springs each having the form of a zig-zag strip.

Many other variations and modifications may be made in the apparatus andtechniques hereinbefore described, both by those having experience inthis technology, without departing from the concept of the presentinvention. Accordingly, it should be clearly understood that theapparatus and methods depicted in the accompanying drawings and referredto in the foregoing description are illustrative only and are notintended as limitations on the scope of the invention.

I claim as my invention:
 1. A filter screen apparatus for use in an airoutlet of a particle production apparatus, said filter screen apparatuscomprising:a plurality of closely spaced resiliently deformable filterelements comprising coil springs mountable across the air outleteffective to collectively releasably receive and hold fines carried inthe air passing through the air outlet of the particle productionapparatus; and vibrating means for resiliently deforming the filterelements effective to dislodge and release fines held on mounted filterelements.
 2. The filter screen apparatus as claimed in claim 1, whereinthe resiliently deformable filter elements are in extended condition. 3.The filter screen apparatus are claimed in claim 2, wherein the coilsprings are extended to from 2.5 to 3 times their unextended length. 4.The filter screen apparatus as claimed in claim 1, wherein theresiliently deformable filter elements are provided with atetrafluoroethylene coating.